Density of mechanisms within the flexibility window of zeolites

V. Kapko, C. Dawson, I. Rivin, Michael Treacy

Research output: Contribution to journalArticlepeer-review

16 Scopus citations


By treating idealized zeolite frameworks as periodic mechanical trusses, we show that the number of flexible folding mechanisms in zeolite frameworks is strongly peaked at the minimum density end of their flexibility window. 25 of the 197 known zeolite frameworks exhibit an extensive flexibility, where the number of unique mechanisms increases linearly with the volume when long wavelength mechanisms are included. Extensively flexible frameworks therefore have a maximum in configurational entropy, as large crystals, at their lowest density. Most real zeolites do not exhibit extensive flexibility, suggesting that surface and edge mechanisms are important, likely during the nucleation and growth stage. The prevalence of flexibility in real zeolites suggests that, in addition to low framework energy, it is an important criterion when searching large databases of hypothetical zeolites for potentially useful realizable structures.

Original languageEnglish (US)
Article number164304
JournalPhysical Review Letters
Issue number16
StatePublished - Oct 12 2011

ASJC Scopus subject areas

  • Physics and Astronomy(all)


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